The mitral valve is located between the left atrium and the left ventricle of the heart. During normal operation, the mitral valve opens during diastole, allowing blood to flow from the left atrium into the left ventricle. During systole, the mitral valve closes, causing high pressure blood to exit the left ventricle through the aorta. Mitral valve regurgitation is a cardiac condition in which the posterior leaflet of the mitral valve does not fully contact the anterior leaflet of the valve during systole, thus a gap remains between the leaflets of the mitral valve during systole. The gap remaining between the leaflets allows retrograde blood flow to pass from the left ventricle into the left atrium through the mitral valve. Thus, mitral regurgitation reduces the volume of blood pumped out of the heart to the aorta during each cardiac cycle, thus reducing the efficiency of the heart. Mitral regurgitation may exist for any of several reasons, including congenital malformations of the valve, ischemic disease, or effects of cardiomyopathy, such as dilated (congestive) cardiomyopathy (i.e., enlarging of the heart).
Conventional techniques for treating dysfunctions of the mitral valve typically include highly invasive, open heart surgical procedures in order to replace or repair the dysfunctioning mitral valve. Some surgical procedures include the implantation of a replacement valve (e.g., animal valve or artificial mechanical valve). Other techniques include the use of annuloplasty rings which are surgically placed around the annulus of the mitral valve within the chamber of the heart and sutured into place. The presence of the annuloplasty ring alters the geometry of the annulus of the mitral valve in order to improve coaptation of the leaflets of the valve. Another surgical technique which requires accessing one or more chambers of the heart is leaflet coaptation. Leaflet coaptation (e.g., Alfieri edge-to-edge repair) is a surgical procedure in which the valve leaflets are sutured together (e.g., bow-tie suture) to improve coaptation of the leaflets. A further surgical technique includes extending a tensioning cord across a chamber of the heart to alter the geometry of the heart chamber. The tensioning cord, which extends through a chamber of the heart, and thus is in contact with blood in the heart chamber, pulls opposing walls of the heart toward one another to reduce heart wall tension and/or reposition the papillary muscles within the chamber. These techniques typically require opening the heart and/or entering one or more of the chambers of the heart to gain direct access to the mitral valve.
Therefore, it is desirable to devise a less invasive technique for treating mitral valve regurgitation. Namely, it is desirable to devise a passive device which may be positioned exterior of the heart to alter the geometry of the annulus of the mitral valve without the need to gain access to the interior of the heart. Thus, the device may be placed in contact with the epicardial surface of the heart without being in contact with blood within the heart.